DNA FRAGMENTATION IN DIFFERENT FISH SPECIES: A POLLUTION ASSESSMENT TOOL FOR AQUATIC TOXICOLOGY

Intense pollution being contributed by human is not only threatening irrigation and ground waters but also terrestrial and aquatic life. The present study was planned to assess the pollution level through percent (%) DNA fragmentation in fish organs (kidney, liver, gills, muscle) of (Wallago attu, Sperata sarwari, Rita rita, and Labeo rohita) collected from River Chanab in polluted and control (Fish Seed Hatchary, Satiana Road, Faisalabad). samples and to assess the impact of habitat (heavy metal toxicity) on the quality of DNA and contribution of weight (duration of exposure to habitat) on % DNA fragmentation. The fish sampling was random so the sampled fish were distributed into three different weight categories to differentiate the impact of the pollution with respect to duration of the exposure to the habitat. The fish samples were processed in the Research laboratory,department of Zoology, Government College University, Faisalabad. After morphometric measurements, each fish specimen was dissected to collect kidney, liver, gills and muscle specimens. Fragmentation was examined spectroscopically and heavy metals by atomic absorption method. The data was analyzed with the help of ANOVA (2 factor CRD and 2 Way) and Pearson's coefficient of correlation.

It was observed weight has significant effect on %DNA Fragmentation as weight of fish is proportional to the age of fish and good feeding habit(Table1). The different fish organs i.e. kidney, liver, gills and muscles analyses revealed that there was an increasing trend of % DNA Fragmentation in all the fish organs of different weight categories, whereas organs and their interaction showed highly significant effect (P<0.01) compared with control samples where no DNA fragmentaion was observed. The weight has a positive and highly significant (P<0.01) correlation on %DNA fragmentation in kidney, liver, gills and muscle. It was observed that lead (pb), copper (Cu), nickel (Ni) and cadmium (cd) levels (mg/kg) in wallago attu, Sperata sarwari. Labeo rohita and Valgarius valgarius within different weight categories, organs and their interaction were highly significantly different (P<0.01). The percent DNA fragmentation values observed for muscles tissue of fish samples were under the normal values. It may be due to the low bioaccumulation of heavy metals and organic pollutants in fish muscles tissue as compared to kidney, liver and gills. DNA damage of aquatic organisms living in polluted environments can be used as a biomarker of the genotoxicity of toxic agents to organisms.